Dwight E Zongker

US Patent:

47096187, Dec 1, 1987

Filed:

Oct 2, 1985

Appl. No.:

6/783119

Inventors:

Dwight E. Zongker - Plevna KS

Assignee:

The Cessna Aircraft Company - Wichita KS

International Classification:

F15B 1122
F15B 1307
B66F 346

US Classification:

91 31

Abstract:

A self-leveling series type hydraulic system including boom and bucket valves which separately control boom and bucket cylinders and a flow divider valve positioned in the exhaust flow path of the rod end of the boom cylinder. The flow divider valve splits the flow sending a portion of it to the cap end of the bucket cylinder so as to maintain the bucket in a level condition during raising of the boom with the remaining flow connected to one of the boom valve motor ports. An improved boom lower circuit which bypasses the flow divider valve as the boom is lowered to achieve a faster boom lower rate and the inclusion of an unloading valve in the bucket circuit which includes the dual function of preventing cavitation and relieving high pressure.